The process of injecting fluids into cracks of rocks to recover oil deposits is known as fracking. To arrive at this answer, I analyzed the options provided: restoring, drilling, cementing, and fracking. By eliminating the options one by one, we can determine that restoring and cementing are not the correct answers. Drilling is the process of creating a hole in the earth's surface to access oil or other resources, which does not involve injecting fluids into cracks. Therefore, the correct answer is fracking.
